The invention relates to a radiometric measuring device.
Conventional radiometric measuring devices, for example for measuring the filling level or density, which signal their measured or process values via a current interface or a current output (4-20 mA), require an energy supply which is separate from the current interface or the current output on account of their comparatively high energy requirement.
The invention is based on the object of providing a radiometric measuring device which can be used as flexibly as possible.
The invention achieves this object by means of a radiometric measuring device having: a scintillator; at least one semiconductor photodiode, the at least one semiconductor photodiode being optically coupled to the scintillator; a signal evaluation unit which is electrically coupled to the at least one semiconductor photodiode and is designed to determine a measurement variable on the basis of a measurement signal which is generated by way of the at least one semiconductor photodiode; and an interface, the radiometric measuring device being able to be coupled to at least one receiver by way of the interface for the purpose of interchanging data; wherein the radiometric measuring device is designed to be supplied with electrical energy solely via its interface.
The radiometric measuring device may be, for example, a radiometric scintillation detector for detecting gamma or neutron radiation for measuring the filling level or density in the process industry.
The radiometric measuring device has one or more conventional scintillators. In this respect, reference is also made to the relevant technical literature.
The radiometric measuring device also has one or more semiconductor photodiodes, the semiconductor photodiode(s) being optically connected to the scintillator(s).
The radiometric measuring device also has a signal evaluation unit, for example in the form of a microprocessor and/or signal processor. The signal evaluation unit is electrically coupled to the at least one semiconductor photodiode. The signal evaluation unit is designed to determine, in particular continually (continuously) and without a measurement pause, a measurement variable on the basis of a measurement signal, for example in the form of measurement pulses, which is generated by the at least one semiconductor photodiode. For this purpose, it is possible to determine, for example, a counting rate of pulses which are generated by means of the semiconductor photodiode, in which case a filling level, a density, etc. is calculated on the basis of the counting rate. In this respect, reference is also made to the relevant technical literature. In particular, the radiometric measuring device is designed to measure continually and without a measurement pause.
The measurement variable may be, for example, a filling level, the density and/or a mass flow. The measurement variable is preferably directly determined in the radiometric measuring device itself, that is to say not only intermediate measurement variables are determined which are then used in the receiver to determine the measurement variable.
The radiometric measuring device also has an electrical interface, the radiometric measuring device being able to be coupled to at least one receiver by means of or via the interface for the purpose of interchanging data in a unidirectional or bidirectional manner. The measurement variable or its value, for example, can be transmitted to the receiver via the interface. During operation, electrical interface energy is available at the interface and is fed, for example, into the interface by the receiver by virtue of the latter impressing a voltage or a current, for example.
The radiometric measuring device is designed to be supplied with electrical energy solely via its interface. In other words, the radiometric measuring device is supplied with electrical (operating) energy solely via the interface. Further energy supplies, for example in the form of dedicated power supply units, are absent.
The radiometric measuring device may have a voltage supply device, the voltage supply device being electrically coupled to the interface and being designed to generate one or more supply voltages for the radiometric measuring device solely from a voltage present at the interface and/or solely from a current flowing via the interface. The supply voltage or voltages/currents derived from the supply voltage can be used to supply all electrical components of the radiometric measuring device.
The voltage supply device may have a voltage converter, for example in the form of a DC/DC converter, for converting the level. The voltage converter may have a step-up part and/or a step-down part. The voltage generated by the voltage converter can be used, for example, as the supply voltage for a semiconductor sensor, for example in the form of an SiPM.
It goes without saying that the voltage supply device may also have a plurality of DC/DC converters or voltage converters for converting the level, for example a voltage converter for generating voltages of greater than 20 V and a further voltage converter for generating voltages of less than 6 V.
The interface may be an analog current interface, for example a so-called 4-20 mA current loop. The latter may be designed, for example, according to the Namur standards NE006 and NE043.
The interface may also be a digital current interface or a mixed analog/digital interface (HART communication).
The interface may be a conventional field bus interface.
The interface may be a two-wire interface.
The radiometric measuring device may contain, for example, the following interfaces for process connection: Modbus interface, Profibus interface, HART interface, FOUNDATION field bus interface, Ethernet interface.
The at least one semiconductor photodiode may be a semiconductor photodiode with internal amplification, for example an avalanche photodiode (APD) or a silicon photomultiplier (SiPM).
The invention relates to a radiometric measuring device, for example in the form of a radiometric scintillation detector, for detecting gamma or neutron radiation for measuring the filling level or density in the process industry. The radiometric measuring device comprises a scintillator, one or more semiconductor photodiodes with internal amplification (APD or SiPM) and a signal processing and transmission unit. On account of the properties of the semiconductor diodes, the radiometric measuring device can be designed in a very energy-saving manner. It is therefore possible to supply the radiometric measuring device solely via its interface, for example with the electrical power available in a 4-20 mA current loop. As a result, the radiometric measuring device can also be designed in the intrinsically safe ignition protection type for applications in explosive regions and can be used in all zones, including zone 0.
The radiometric measuring device may have disintegration compensation, as a result of which it is possible to compensate for the decrease in activity as a result of the disintegration of a radioactive nuclide used for the measurement. For this purpose, the radiometric measuring device may have components which make it possible to determine the date and the time, for example a real-time clock or a radio receiver which is designed to receive GPS signals, for example, or as a receiver for receiving DCF77, MSF, JJY or WWVB signals.
The radiometric measuring device may have a non-volatile data memory for storing calibration data (application calibration data or electrical component calibration data) or manufacturing data.
The radiometric measuring device may have one or more semiconductor sensors which is/are suitable for directly detecting ionizing radiation or for detecting secondary radiation (for example scintillation light) which has been converted by means of one or more scintillators.
The radiometric measuring device may have a control device which may contain one or more functional blocks which generate one or more control signals.
One functional block may generate a control signal, for example, on the basis of the temperature or characteristic properties of the spectrum, which control signal can be used to stabilize the measuring device.
A further functional block may generate a second control signal for controlling the functional unit which transmits process values.
These functional blocks may also be distributed among a plurality of control units.
The functional unit which transmits process values may transmit its information to the receiver (for example supply isolator, PLC or process control system) in an analog or digital manner.
The radiometric measuring device may have an Ex i barrier for limiting current, voltage and power. The Ex i barrier has the property of blocking electrical energy, which is contained or stored in the measuring device, in the event of a fault or converting it into heat, with the result that it is not forwarded to the connection terminals of the measuring device and can cause an ignitable mixture to explode. With respect to the configuration of the barriers, reference is made to the relevant technical literature.
The radiometric measuring device is supplied with electrical energy solely via its interface during normal operation or measurement operation, during which it determines the measurement variable.
The radiometric measuring device may be designed in the Ex i ignition protection type or may combine this ignition protection type with further ignition protection types (for example Ex m), that is to say the radiometric measuring device may be designed in the intrinsically safe ignition protection type or as a combination of the intrinsically safe and encapsulated or intrinsically safe and pressure-resistant ignition protection type.
According to one embodiment, the interface is a current interface, the radiometric measuring device being designed to code and/or transmit the measurement variable by means of the current consumption of the radiometric measuring device. For this case, the radiometric measuring device has at least one electrical energy store, the at least one electrical energy store being able to be (re)charged by means of a charging current. The electrical energy store may be, for example, a rechargeable energy store of a real-time clock of the measuring device.
The radiometric measuring device also has a charging current controller which is designed to set the charging current on the basis of the measurement variable.
The radiometric measuring device may have a real-time clock (RTC), for example in order to determine the date needed for disintegration compensation and the time. For this case, the energy store is designed to supply the real-time clock with electrical energy when (as soon as) no (more) energy is provided via the interface. In other words, the energy store is used as a buffer store for the real-time clock.
The radiometric measuring device may have at least one adjustable ballast resistor (load) which can be used to control the current consumption of the radiometric measuring device. The charging current controller is designed to set a resistance value of the at least one ballast resistor on the basis of the measurement variable, that is to say the resistance value can be used as the manipulated variable of the charging current controller.
The charging current controller may be designed to set the resistance value of the at least one ballast resistor on the basis of the measurement variable in such a manner that a current through the at least one ballast resistor becomes minimal and the charging current becomes maximal as long as a storage or charging capacity of the electrical energy store has not yet been exhausted. If the storage or charging capacity of the electrical energy store has been exhausted, the charging current can be set to zero and excess electrical energy can be converted into thermal energy in the at least one ballast resistor.
The signal evaluation unit may be designed to check the determination of the measurement variable for possible faults, the radiometric measuring device being designed to deactivate those assemblies of the radiometric measuring device which are provided for determining the measurement variable in the event of a fault.